what to do with microbore pipes

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Hello we would like to change the
central heating to a sealed system.
The pipework is microbore from the early
1980s. Do you think the microbore will definetly
need changing or can it be kept with a combi?

regardd
 
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Depends ... if the system is nice and clean then shouldn't be an issue. The key here I find though is what is meant by microbore.

IME, true microbore was 8mm copper pipe that then fed into end feed 4 port brass manifolds soldered onto the end of 22mm pipes. A truly clean and well kept system is quite happy on that kind of system but good ones are rarer than hen's teeth. Most have leaked, been inadequately inhibited, been bashed about at the radiator tails and they leaked at the snap reducers etc they have then all ended up pretty badly sludged up. You try and clean it and the pipe, especially at the manifolds become clogged and the system never heats up properly again. You also are restricted to the size of radiator they can happily supply.

10mm small bore systems were a bit better but still used end feed manifolds with the same issues as the 8mm but some used 22mm to 10mm reducers, which holds up better to cleaning and flushing but again the narrower bore can still get clogged up and has the same issue at the valves, bent pipes/leaky reducers etc.

For an all round good system that can happily be flushed and cleaned in the future, 22mm mains with 15mm branches would be my recommendation.
 
thanks.

we are renovating the house so i would worry about leaks in a newly redecorated house.

In your opinion the cost of replacing pipework in a four
bed three reception two bathroom home how much more in percentage would it add to the cost of changing system to combi and changing all radiators?

thanks
 
if all soldered joints and everything is working you dont need to worry
 
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If you're doing a full back to bricks renovation the price difference between using existing pipes and renewing will fade into insignificance. Plastic pipe is the devils work but if propertly planned can be cheaper than copper (plastic is most cost effective as a manifold system with no joints between manifold and radiator)
 
the main reason for changing the system
would be because we are worried about having tanks in the loft and the chance of burst pipes.
the current boiler was installed in 2007 and it is a potterton promax sl. the other issue is we dont want hot water on a timer.

the current system warms up the house pretty quick so i am in two minds whether to leave it alone.

what would you do? leave current boiler and c heating in place and add a megaflow for hot water?

piping is 35 years old

thanks
 
Take it this house is new to you?
First one- lag the tanks and pipework in the loft and they'll be fine. (don't lag under the tanks tho)
2nd- hot water. If flow rate and pressure are OK on the existing setup then leave it alone. Any particular reason for not wanting hot water on a timer- again if the cylinder is well insulated then running costs are quite low. Megaflow would need heat from somewhere (timer) and they get a mixed press...also (like combis) they rely on good mains pressure and delivery rate so check that before you do anything
Pipework rads etc- if they work and are where you want them then leave them be, if you don't like them then change them
 
Take it this house is new to you?
First one- lag the tanks and pipework in the loft and they'll be fine. (don't lag under the tanks tho)
2nd- hot water. If flow rate and pressure are OK on the existing setup then leave it alone. Any particular reason for not wanting hot water on a timer- again if the cylinder is well insulated then running costs are quite low. Megaflow would need heat from somewhere (timer) and they get a mixed press...also (like combis) they rely on good mains pressure and delivery rate so check that before you do anything
Pipework rads etc- if they work and are where you want them then leave them be, if you don't like them then change them

yes we have just bought the house.

i had a look in the loft today and there are three tanks.
i was expecting only two of them, any reason why a third would be there?

also i am not sure where water to the tanks can be isolated, is this generally via a tap at the tsnk itself or should the valves be in the airing cupboard?

in your opinion how long dies microbore piping last?

thanks
 
3 tanks- are all the cold taps off the rising main? (Find a friend, get him/her to go round the house turning taps on and off while you lurk in the loft watching which tank level drops when). Small tank should be F & E for the heating, 1 large tank hot water header, 2nd large tank poss cold water header, poss additional hot water.
Service valves on the tank supplies- might be non-existent, might be at the tank, might be in the airing cupboard. I've always fitted them in the airing cupboard for ease of access. You may find service/isolation valves on the tank outputs (for the hot and cold anyway, not on the F & E)- these are handy, they allow you to strip a tap without draining the header tank/hot water cylinder. If you have a service valve on the supply to F & E make it tamper resistant (if that one runs dry it could cause problems).
What size is your 'microbore'- 8mm, 10mm, 12mm? No reason any of it shouldn't last 50 years (inhibitor added), depending on water hardness in your area the smaller bore might be more prone to furring up (though smaller bore = higher water velocity for given heat transfer so may not be a problem). I've not used much microbore, odd bits of 12mm to get through convoluted routes & the oldest bit is now 28 and still works.
 
3 tanks- are all the cold taps off the rising main? (Find a friend, get him/her to go round the house turning taps on and off while you lurk in the loft watching which tank level drops when). Small tank should be F & E for the heating, 1 large tank hot water header, 2nd large tank poss cold water header, poss additional hot water.
Service valves on the tank supplies- might be non-existent, might be at the tank, might be in the airing cupboard. I've always fitted them in the airing cupboard for ease of access. You may find service/isolation valves on the tank outputs (for the hot and cold anyway, not on the F & E)- these are handy, they allow you to strip a tap without draining the header tank/hot water cylinder. If you have a service valve on the supply to F & E make it tamper resistant (if that one runs dry it could cause problems).
What size is your 'microbore'- 8mm, 10mm, 12mm? No reason any of it shouldn't last 50 years (inhibitor added), depending on water hardness in your area the smaller bore might be more prone to furring up (though smaller bore = higher water velocity for given heat transfer so may not be a problem). I've not used much microbore, odd bits of 12mm to get through convoluted routes & the oldest bit is now 28 and still works.

would you re use existing microbore in a pressurized system?
 
No specific reason why you shouldn't, if the rads work now they'll work with a new boiler
 
We had attic tanks in our house thirty one years. Why should there be a problem?

The attic pipework should be well lagged, if not, make it so.
Foam, plus felt for corners and fittings, all well tied on with string.
Put polystyrene slab around the tanks, leave no gaps.
As has been said, don't insulate under the tanks, nor any loft insulation under them.

Check the inhibitor in the system, check the concentration, most important. Lack of inhibitor kills all systems.

The cylinder, if old, is worth changing for one with integral foam insulation. Infinitely better than a loose jacket and will soon pay for itself.
 
As suggested, if the system is clean and working then there shouldn't be an issue.

Some installers don't like it due to issues that can be found when flushing or will caveat it going from open vented to sealed.

You really need to get an installer in to have a good look and give you advice, being onsite they will be better placed to advise you. Try and get some local recommendations.
 
As suggested, if the system is clean and working then there shouldn't be an issue.

Some installers don't like it due to issues that can be found when flushing or will caveat it going from open vented to sealed.

You really need to get an installer in to have a good look and give you advice, being onsite they will be better placed to advise you. Try and get some local recommendations.

how long can these pipes last providing the system has been looked at well?
currently 35 years old.

thanks
 

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